Use of Intelimer® Microcapsules to Control the Release of Agricultural Products and Reduce Leaching

Landec Corporation has developed a family of polymers (Intelimer®) with unique properties that are currently being used in the microencapsulation of agricultural pesticides. Landec is developing uses for its proprietary polymers, which have a temperature switch built into them. Below the switch temperature the polymers have a very low permeability to the diffusion of active ingredients and above the switch they are quite permeable. This property allows the preparation of capsule suspensions (CS) that release active ingredients in response to small changes in temperature. Many different classes of pesticides including an acetanilide (alachlor) and a sulfonyl urea herbicide have been encapsulated.

Soil temperature initiates many biological processes. If the delivery of the pesticide coincides with these processes, the most effective control of the pest will occur. In application practices where the pesticide is applied before planting, degradation processes deplete the pesticide, necessitating the need for a larger amount of pesticide to be applied, to give a particular window of control (10 days to 45 days). The use of temperature activated release of pesticides may be the most cost effective use of a pesticide. The soil can be treated prior to planting, but release of the pesticide will not occur until the appropriate temperature is reached. Microcapsules utilizing this release mechanism offer many advantages over conventional formulations, such as a reduction in leaching, protection from environmental degradation and reduced application rates.

In column leaching and field trial studies, CS's of a sulfonyl urea and an acetanilide controlled migration of the active within the top 5 or 7.5 centimeters of soil, while wettable granules and wettable powders had 3 to 8 times further migration in the soil. Test results illustrate that CS's can significantly decrease groundwater leaching potential of herbicides. A temperature-activated “on/off” response in biological control was observed in temperature controlled growth chamber studies.